Gas Fireplace Pilot Light On But Won’t Ignite

Last Updated on August 14, 2021 by Kimberly Crawford

There are a lot of reasons why homes are installed with fireplaces. For one, it really can become the focal point of any room.

Another is that it makes the home ambient and raises up its aesthetic value. As such, it comes as quite a hassle if the gas fireplace stops working. One of the problems of a gas fireplace is when the pilot light is on but would not ignite. 

To check this, you must check your home’s fuse or breakers. If it still does not ignite even if the power supply is stable, it might be time to replace the fuse or repair the electric ignition.

But sometimes, the problem is more than this, so in this post, we will round up all the things that you need to look out for when it comes to gas fireplace. 

Related: Electric Fireplace Guide 101- What’s, Why, How’s of These Fire Mimickers

Reasons your gas fireplace pilot light on but will not ignite 

As have been mentioned, there are various reasons as to why a gas fireplace would not ignite even if the pilot light is on. Here are some of the most common reasons why this is happening to your gas fireplace. 

1. Fuse/breaker overload

It is always recommended that the gas fireplace be run in its own breaker. When the circuit breaker is overloaded, your gas fireplace simply would not ignite.

You have to understand that even though it is fueled by gas its electronic ignition (which makes it spark and catch fire) does not ignite without electricity. 

2. Trapped insects and other obstructions

Sometimes, when the pilot tubing has not been lit for quite a while, insects tend to niche on it. This is the reason why it is recommended that the pilot light be left open especially in rural places or those with probable insect infestations. 

3. Gas valve is not on

Even if the pilot light is on if the gas valve is off, do not expect the fireplace to ignite. Always check the main gas if it is turned on.

If it is on and does not work its thing, the gas valve might be faulty. Ask a technician to come and replace it because a faulty gas valve is a major fire hazard. 

4. Gas pressure

There is a required gas pressure for the gas fireplace to maintain its light. If you think that this could be the problem, ask for professionals to come and gauge the gas pressure supplied to your fireplace. 

5. Moisture drip

Moisture or water drip in the gas line dilutes the natural gas that ignites your gas fireplace. When this happens, the pilot light might be on but the fireplace would not ignite or the fire would not stay lit continuously. 

6. Clogged burner ports

When the fireplace is not igniting or if you find an uneven flame or that goes off every now and then, it might be an indicator that your burner ports are clogged and need cleaning. 

7. Worn out thermocouple/thermopile

If you have reset the thermocouple but the pilot light would not go on, the thermocouple might be damaged or needs replacement. But if the pilot is light yet the gas fireplace is not lit, there is a problem with the thermopile. 

How to troubleshoot

There are various ways to troubleshoot the problem of having a pilot light on but the gas fireplace would not ignite. The thermocouple and thermopile troubleshooting is in the succeeding sections so let us just leave it at that. 

Troubleshooting the spark ignitor

  1. Check the gas regulator and check for a stuck valve. 
  2. After straightening the stuck valve, try lighting the pilot light.
  3. Third, bypass the electric ignition and opt for a manual pilot lighting. 
  4. Call for professional help. 

Troubleshooting a faulty vent cap

  1. Check the air draft in the vent cap. Purge the air and try lighting the pilot light. 
  2. If the flame is still extinguished, replace the vent cap. 
  3. If you installed a new one, get a draft stopper to stop this from happening again. 

Troubleshooting a gas fireplace that would not ignite

  1. Check the main gas valve if it is on. 
  2. Check out the pilot light system. Clean it if it has clogs. 
  3. Check again if it works after cleaning. If it does not, seek professional help. 

Troubleshooting the pilot tubing

  1. Check debris clogging and clear debris right away. 
  2. Check your thermocouple next. If it is less than 25 millivolts, have it replaced. 

What is a thermocouple?

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Most people always confuse the thermocouple with the thermopile. A thermocouple is the sensor that supplies gas to the pilot light and ensures gas flow through the gas valve. On the other hand, the thermopile is the one that opens the gas valve when the gas fireplace is turned on. 

When it comes to function, both the thermocouple and the thermopile work by converting heat to electricity. But in terms of electricity generated, the thermopile produces more electricity than the thermocouple. 

How do you know if you have a bad thermocouple?

The best measure for diagnosing a bad thermocouple would be using a multimeter. If you have a good thermocouple, it will register 25 millivolts or higher. If it is less than that, it already indicates that you should replace the thermocouple.

If the thermocouple is not the problem, next check the thermopile. Using the same multimeter, check if it registers 300 millivolts. If it is below that, it needs replacement. 

How long does a thermocouple last on a gas fireplace?

So, as previously said, the thermocouple is a heat sensor which transfers electricity to the gas valve. It is in the gas furnace and keeps the gas valve open through electricity whenever the pilot is on.

On average, the thermocouple lasts for at least 10 years. Regularly checking your thermocouple’s gauge should undergo a four-year check cycle to make sure that everything is working. 

Related: 20+ Types Of Fireplaces and Their Names

Should I replace my thermocouple/thermopile right away?

No, because you can clean them first. Sometimes, you just need to remove carbon deposits from the TC and the TP. It is also way cheaper to clean them both first.

How to clean? Just turn off the gas supply first and then clean it with fine-grit sandpaper and stainless-steel brush. Take as much soot as you can. If the cleaning does not work, that is the only time that you replace them. 

What is the right pilot light color?

When the pilot light is lit, the flame color must be a steady blue (or 90% blue and 10% yellow). The flame must touch and surround the thermocouple and thermopile. If ever the flame becomes red or yellow, that could mean that your gas is contaminated. 

How much does it cost to replace a thermocouple on a gas fireplace?

If you hire a professional in replacing your thermocouple, you could spend a range of $70-150. If you have the skills and want to do it on your own (with the aid of a user’s manual, of course), you would only spend at least $20-50

How do you reset the pilot light on a gas fireplace?

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The good thing about resetting the pilot light on a gas fireplace is that you can do it in just two steps only. 

  1. Locate the gas control button. Hold down the button while simultaneously holding your lighter towards the pilot tube’s end. If you have done it right, the fireplace should catch flame as soon as the flame from the lighter is close enough to the pilot tube. 
  2. Make sure that holding the button down is done for a duration of 20 seconds. This gives the thermocouple enough time to heat up. 

Can I manually light my gas fireplace?

Yes. So how do you light a gas fireplace without electricity? Here are the steps to follow. 

  1. This is basically the role of the pilot light. Turn on the knob from off to pilot to turn on the gas fireplace. Newer models come with battery-powered igniter. You can use it to manually ignite the gas fireplace when there is no electricity. 
  2. Push in the pilot button to manually send gas to the fireplace. Do it for several times until it catches flame. Sometimes, it may take multiple times especially if the gas fireplace was not used for a long time. 

Here is a visual for you to execute it properly. 

Is it dangerous if pilot light goes out on the gas fireplace?

It could be, especially if the pilot light goes out and the gas valve is still pumping. If there is a gas buildup happening out there so when the pilot light is reignited, it could become a source of a serious fire hazard or explosion. 

The silver lining into this however, is that newer models of gas fireplaces come with a fail-safe device which automatically shuts off the gas valve when the pilot light system stops working. 

Should gas fireplaces without a standing pilot light system be turned on every time? 

Even if it has a standing pilot light system, you should turn it on seasonally except for those living in rural areas where insects could niche in the pilot tubing.

If it does not have a standing pilot system, turning it off saves you energy, money, as well as from a potential fire hazard. 

Is it safe to leave the gas fireplace on overnight? 

If it undergoes regular cleaning and maintenance, you can leave the gas fireplace on overnight. But if you are not sure about this, it is not recommended because you are risking yourself and your family of carbon monoxide poisoning so make sure that you leave it out before you go to bed. 


You might think that there is no complexity behind gas fireplaces but the things we covered here surely proves that there is more beyond it. The reasons behind a gas fireplace with the pilot light on that does not ignite are more than one. 

At the end of the day, consulting your user’s manual before calling a professional or fireplace technician can save you money, time, and effort. But if you are not the mechanical type and it is your first time to do it, only consult with trusted professionals.